JPS58214007A - Blind nut and tool for forming fitting hole of said nut - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blind nut and a tool for forming a mounting hole thereof.

A member 1 that is thin and difficult to operate from both sides, such as a reinforcing member 4 for fixing an automobile bumper 2 as shown in FIG. 1, is difficult to thread and insert and position a nut inside. For this reason, it is difficult to fasten the above-mentioned members using an ordinary nut stand and pole.

Therefore, a nut 10 (herein referred to as a blind nut) that can be fixed from one side is used. The blind nut 10 is made of a hollow cylindrical body made of a plastically deformable material, has a female thread 12 cut in its front inner diameter portion, and has a flange radially extending outward at its rear end. This blind nut 10 is connected to one fastened member 16
After inserting into the mounting hole from one side, the nut is bulged outward as shown in FIG. 2 by compression in the axial direction, and is caulked and fixed.

Thereafter, the bolt 8 passed through the other fastened member 18 is screwed together to perform the fastening operation.

However, with conventional blind nuts, the outer circumferential surface of the nut and the inner circumferential surface of the mounting hole of the fastened member are only in concentric surface contact, so a large torque is applied to the blind nut when tightening the bolt using an impact wrench, etc. If the bolt ends are brought into contact with each other and an axial force is applied, the blind nut, which has been secured by caulking, may spin idly.

Therefore, an object of the present invention is to further stabilize the caulking of the blind nut.

In order to achieve the above object, according to the present invention, a concave groove cut out in a radially outward direction is provided on the outer peripheral surface of the attachment hole of the fastened member,
A blind nut is inserted into the mounting hole, and the intermediate wall portion of the blind nut is bulged out in a radial direction including the mounting hole, and the member to be fastened is crimped and held between the bulged portion and the flange portion. This groove can be formed in a pre-formed mounting hole (usually a round hole) using the tool described below. That is, the tool for forming the recessed grooved mounting hole of the blind NAND includes a round guide portion that contacts the inner circumferential surface of the blind NAND mounting hole previously formed in the member to be fastened, and a tool disposed behind the guide portion. It consists of a flange portion that can be inserted into the mounting hole, and a blade that is formed on the outer front edge of the flange portion to protrude radially outward and has a cutting edge angle of 15 to 40°.

According to the present invention, since a concave groove notched radially outward is provided on the surface of the mounting hole of the fastened member, the nut mounting hole becomes irregularly shaped, and the nut outer peripheral surface (intermediate wall @) is plastically deformed when the nut is swaged. Since it bulges out and fits into the groove, it will not slip even if a large torque is applied during bolt tightening.

Forming a groove using the tool of the present invention does not require a die for the receiver, there is almost no surface erosion of the fastened member, and the groove is formed from the outside on the fastened member of the hollow object to which the fried nut is to be fixed. I can do it.

The present invention will be described below with reference to the accompanying drawings.

First, with reference to FIGS. 3 and 4, the tool 2 according to the present invention
0 and the blind nut mounting hole 22 will be explained. The irregularly shaped mounting hole 22 as shown in the figure is made by first forming a round hole from one side of the fastened member 16 using a drill (not shown), and then using the tool 20 shown in FIGS. 3 and 4 to form a round hole. A groove 24 notched radially outward is formed on the circumferential surface of the hole. The grooves 24 shown in the figure have a semicircular shape, and a total of 4 grooves are formed, but it is also possible to have a shape other than this, such as a triangle, or a number other than the above, such as 1 to 3, or 5 or more. It is.

The tool 20 mainly consists of a guide section 26 located at the front, a grip section 28 located at the rear, a flange section 30 located between the two, and a cutting edge 32 located at the front edge of the outer periphery of the flange section 30. Become.

The guide portion 26 has a truncated conical tip for easy insertion, and the rest of the guide portion 26 has a substantially quadrangular prism shape. Each corner of the square column is rounded so as to make surface contact with the inner peripheral surface of the round hole. Therefore, alignment of the tool 20 is completed by inserting the guide portion 26 into the round hole. This flange portion 30 has an outer diameter approximately equal to the inner diameter of the round hole so that it can be inserted into the round hole of the member to be fastened 16, and a cutting edge 32 is provided at the front edge of the outer circle. One or more cutting edges 32 are provided along the outer periphery of the flange portion 30. The tool angle or rake angle of the cutting edge 32 is 15 to 40 degrees, preferably 80', allowing cutting from one side. The grip portion 28 is formed into a cylindrical shape so that it can be easily attached to a predetermined punching device (not shown). When the tool 20 with the guide portion 26 inserted into the round hole of the member to be fastened 16 is struck by a predetermined punch device, the cutting blade 32 comes into contact with the periphery of the round hole of the member to be fastened 16, and the tool 20 Notch 16,
The round hole is used as the irregularly shaped mounting hole 22.

As shown in FIG. 6, the blind nut 10 is inserted from one side into the mounting hole 22 thus modified. The blind nut 10 is a hollow, substantially cylindrical member made of a plastically deformable material, and has a flange portion 14 extending radially outward at one end. The inner diameter portion 12 of the blind nut 10 is composed of a female threaded portion 12 provided near the end opposite to the flange portion 14, and a bolt guide portion 34 located on the flange portion 14 side.

As shown in Figure 1, the bolt guide portion 34 has an inner diameter slightly larger than the female thread portion 12, and therefore the wall portion 36 corresponding to the bolt guide portion 34 is also thin.

The outer diameter of the cylindrical portion of the blind nut 10 is slightly smaller than the inner diameter of the mounting hole 22 of the member to be fastened, so that the blind nut 10 can be inserted into the mounting hole. As shown in FIG. 6, the blind NAND 10 fitted to the fastened member 16 is compressed in the axial direction, and the thin wall portion 36 bulges radially outward as shown in FIG.

As shown in the figure, the bulging portion 38 has a substantially U-shaped cross section, and the member 16 to be fastened is caulked and compressed between the flange portion 30 and the U-shaped bulging portion 88. In this way, the blind nut 10 is fixed to the member 16 to be fastened, but a part of the plastically deformed thin wall portion 36 bites into the groove 24 of the mounting hole 22, so even if a large torque is applied to the blind nut 10. These biting portions into the grooves 24 prevent the blind nut 10 from idling.

[Brief explanation of drawings]

Figure 1 is a perspective view showing an application example of a blind nut, Figure 2 is a sectional view showing a fastening method using a blind nut and bolt, and Figure 3 is a side view showing a tool for forming a modified mounting hole. 4 is a front view of the tool shown in FIG. 3 viewed from the axial direction, FIG. 5 is a plan view showing the blind nut inserted into the mounting hole formed by the tool shown in FIG. 3, and FIG.
The figure is a sectional view taken along the line ■--■ in FIG. 5, and FIG. 7 is a sectional view showing the blind nut after caulking. 8... Bolt 10... Blind nut 12... Threaded portion 16... Member to be fastened 20... Tool 22...・Mounting hole 24...Concave groove Applicant: Aisin Seiki Co., Ltd. Agent Patent attorney Asamichi Kato Figure 1 Figure 2 Figure 3 Star Figure 5

Claims (2)

[Claims] (1) A blind nut consisting of a hollow cylindrical body made of a plastically deformable material, having a female thread at the front inner diameter portion, and a flange portion expanding radially outward at the rear end;
It is inserted into a mounting hole of a fastened member having a groove cut out in a radial outward direction from the same surface, and the blind nand intermediate wall part is formed with a bulging part formed by bulging out in a radial outward direction including the inside of the mounting hole groove. A blind nut that presses and holds a member to be fastened between the flange portion and the blind nut. (2) a rond-shaped guide portion that contacts the inner circumferential surface of a blind NAND mounting hole preformed on the member to be fastened, and a flange portion arranged behind the guide portion and insertable into the mounting hole;
A tool for forming a recessed grooved mounting hole for a blind nut, comprising a blade protruding radially outward from the external front edge of the flange portion and having a cutting edge angle of 15 to 40 degrees.